JPH02289308A - Manufacture of mortar and concrete - Google Patents

Abstract

PURPOSE:To greatly improve the capacity of mortar or concrete, by a method wherein during falling of a cement composition, spraying is performed homogeneously by making use of a specific quantity of water containing a cement additive or that not containing the cement additive, during that time the cement composition is subjected to treatment where the cement composition receives a shearing action. CONSTITUTION:A powdery cement composition is caused to fall under a state where each ingredient in a homogeneously distributed and dispersed condition by centrifugal force based on rotary motion while the composition is being fed continuously as a specific treatment to the composition. A continuous mixer F is used suitably. Spraying to a cement composition is performed during falling of the cement composition so that water is distributed homogeneously by making use of the water containing a cement additive or that not containing the same at a quantity of 0.1-10pts.wt. on the basis of 100pts.wt. cement. An appropriate quantity of the water is stuck to the surfaces of cement particles and a cement hydrated layer containing etiolinguite or a mineral similar to the etiolinguite is formed on the surface. It is necessary that an interval of time until the powdery cement composition comes into contact with the next kneaded water is made at least three minutes, in the powder cement composi tion to which specific treatment is performed.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a method for producing fresh mortar or fresh concrete by applying special treatment to a powdered cement composition, This invention relates to a method for producing modified mortar or concrete, which is characterized by adjusting the time it takes to knead the material and bring it into contact with water.

[Background technology] Aggregate and mixing water are added and mixed to a cement composition,
When producing fresh mortar or fresh concrete, the use of an AE agent, water reducer, AE water reducer, high performance water reducer, high performance AE water reducer or superplasticizer reduces the water-cement ratio and increases the compressive strength. Although efforts have been made to increase the compressive strength, there are five technical challenges to further increase the compressive strength and improve durability.

As a result of various studies to address these technical issues, the present inventors have found that in producing fresh mortar or fresh concrete, a powdered cement composition is subjected to special treatment, and the resulting powdered cement composition is They succeeded in obtaining modified mortar or concrete by adjusting the time until the mixture comes into contact with mixing water.

[Disclosure of the Invention] The present invention is a method for producing fresh mortar or fresh concrete, in which a powdered cement composition is continuously supplied, and each component of the composition is homogenized by centrifugal force caused by rotational motion. The composition is allowed to fall under conditions in which the composition is dispersed and dispersed, and during the fall, water containing the cement additive or water not containing the cement additive is added at 0.1 parts by weight per 100 parts by weight of the cement composition. ~10 parts by weight is used to homogeneously spray onto the cement composition 1, and the surface of the cement particles is modified by applying a shearing action during the spraying process, and then (Obtained powdered cement composition 1) Mortar or concrete characterized by mixing with aggregate and mixing water in a mixing mixer for a period of 3 minutes or more until the powder comes into contact with the mixing water. A manufacturing method is provided.

The present invention will be explained in detail below.

In the method of the present invention, the powdered cement composition is subjected to special treatment and the time required for mixing the powdered cement composition and bringing it into contact with water is adjusted.
Powdered cement compositions include portland cement,
Hydraulic cement such as alumina cement is used. Preferably, Portland cement is suitable as the above-mentioned hydraulic cement.

Further, as this powdered cement composition, a mixture of this hydraulic cement and an inorganic fine powder can also be used. Examples of the above-mentioned inorganic fine powder include flyadush,
Examples include blast furnace slag powder and fine silica powder. The special treatment for the powdered cement composition is as follows: While the composition is continuously supplied, each component is dispersed in a homogeneous distribution due to centrifugal force due to rotational motion.
It is necessary to drop the composition, and in this case, a continuous mixer can be suitably used.

During the dropping of this cement composition, water containing or not containing a cement additive is used in an amount of 0.1 to 10151 parts per 100 parts by weight of the above cement composition. It is preferable to spray the composition and subject it to a treatment during which it is subjected to a shearing action. This spraying is preferably carried out so that the moisture is distributed homogeneously. As a result, an appropriate amount of water adheres to the surface of the cement particles, and a cement hydration layer containing ettringite or an ettringite-like mineral is formed on the surface.

The powdered cement composition subjected to the above-mentioned special treatment is then brought into contact with mixing water, but at that time, it is necessary to make the contact time for 3 minutes or more. By setting this time to 3 minutes or more, the fluidity of the mortar or concrete after mixing will be significantly increased.
Therefore, the unit water amount for the same consistency is significantly reduced.

Examples of the above cement additives include gluconate, lignin sulfonate, β-naphthalene sulfonate formalin condensate, melamine sulfonate formalin condensate, aromatic aminosulfonic acid-based polymer compound, polystyrene sulfone. Acid acid, hydroxy polyacrylate, αβ
-Copolymers of unsaturated dicarboxylic acids and olefins, copolymers derived from polyethylene glycol monoallyl ether and maleic acid monomers, isobutylene-styrene-maleic acid-based, isobutylene-acrylic acid ester-maleic acid-based, isobutylene- Examples include styrene-acrylic acid ester-maleic acid copolymers, water reducing agents with setting retarding properties, and the like. Examples of water-reducing agents that have set-retarding properties include sugars such as sucrose and glucose. As for the method of adding cement additives, part or all of the amount used in the formulation may be mixed into the powdered cement composition in the process before the above-mentioned special treatment; A part or all of the cement additive can also be added to the water used in the above-mentioned special treatment or the mixing water used in the process of mixing mortar or concrete. In this way, the cement additive can be used, in part or in its entirety, in the material at various stages during the entire mortar or concrete manufacturing process.

The powdered cement composition in the method of the present invention may contain other cement additives commonly used in cement technology, such as setting accelerators, setting retarders, strength enhancers, air volume regulators, antifreeze agents, antifreeze agents, pigments, etc. It is also possible to contain.

Mortar or concrete produced by the method of the present invention has the following properties.

■ When trying to obtain the same consistency, the unit amount of water used is painfully small. Therefore, compressive strength and durability are significantly improved, and drying shrinkage is significantly reduced.

■ Consistency is significantly greater when using the same unit water volume.

■ Improved fluidity and good initial strength development.

■Breathing is reduced and the volume change of concrete after pouring is reduced.

The second property significantly improves the performance of the mortar or concrete and makes it more durable.

The present invention will be specifically described below with reference to Examples.

■ Continuous mixer for early strength Portland cement (manufactured by Mitsubishi Mining Cement) at 18.75 kg/min.
See No. 164631, Japanese Patent Publication No. Sho 62-289225, and Utility Model Publication No. Sho 62-199127. Spiral bottle mixer S
PM-25D improved model (manufactured by Ohyo Kikokai 1)]
An aqueous solution of a formalin condensate of β-naphthalene sulfonate (commercial product) with a concentration of 32.43% was added to
A modified cement composition (A1) was prepared by continuously spraying at a feed rate of 77.5 g/min and subjecting it to the above-mentioned special treatment in the method of the present invention. (The cement composition (At) contains 1% moisture based on the early strength Portland cement used, and 0.4% dry weight as a high performance water reducer.)
This means that 8% is added. This cement composition I
Using I (A l ), the time from immediately after preparation until contact with mixing water was made in 7 cases as shown in Table 1, and in each case, fresh mortar was manufactured by mixing with sand. .

(2) The same amount of early-strength Portland cement as in (2) was subjected to the special treatment in the method of the present invention by continuously spraying water using the continuous mixer described above. That is, by continuously spraying 1% water on early-strength Portland cement,
Cement composition m(A2) was prepared. Regarding this cement composition (A2), immediately after its preparation, a high performance water reducing agent:
The time required for contact with mixing water to which 75% of a formalin condensate (commercially available) of β-naphthalene sulfonate has been added is determined in the seven cases shown in Table 1. Fresh mortar was produced by kneading and mixing.

■ A powdered high-performance water reducer: formalin condensate of β-naphthalene sulfonate (commercially available) is mixed in advance with the same amount of early-strength Portland cement as ■ ■, and the mixture is supplied to the above-mentioned continuous mixer, and water is continuously added. A cement composition (A) with 1% water added to early strength Portland cement
3) was prepared. Using this cement composition (A3), the time from immediately after preparation to contact with mixing water was determined in six cases as shown in Table 1, and in each case, fresh mortar was prepared by mixing with sand. Manufactured.

2) Test of fresh mortar Regarding the fresh mortar obtained in 1) above, JI
Flow values were measured according to SR5201.

A test was conducted on each cement composition (Ai) (A2) or (A3). The test results are shown in Table-1. The comparison in Table 1 is for early-strength Portland cement (manufactured by Mitsubishi Mining Cement@) that is not subjected to the above-mentioned special treatment.
It is.

Examples 4 to 6 1) Manufacture of fresh concrete (D) Using the improved spiral pin mixer SPM-25D shown in Examples 1 to 3, the production of fresh concrete was performed using early strength Portland cement (Mitsubishi Mining Cement "Shunsei"). The above-mentioned special treatment in the invention method was applied, namely, continuous spraying of 1% water to early-strength Portland cement;
A cement composition (B1) was prepared. Regarding this cement composition (B1), the aggregate and kneading water are supplied into a kneading mixer so that they come into contact with the mixing water after 5 minutes have elapsed from immediately after preparation, and kneading is performed. manufactured concrete.

■ Using the same continuous mixer as in ■, water was continuously sprayed onto the early-strength Portland cement to create a cement composition (B2) in which 1% water was added to the early-strength Portland cement.
) was prepared, and after 5 minutes had passed since the preparation, a high-performance water reducing agent: Formalin condensation of β-naphthalene sulfonate 91 (commercial product) (hereinafter abbreviated as BNS) was added to 7 grains of silk and mixed. Aggregate and superplasticizer (
Mixing water to which BNS) was added was supplied into a mixing mixer, and mixing was performed to produce concrete.

1■ 18.75 kg of early strength Portland cement/
An aqueous solution of superplasticizer (BNS) with a concentration of 32.43% was continuously fed at a feed rate of 277.5 g/min to the above-mentioned continuous mixer, and the above-mentioned special treatment was applied. A cement composition (B3) was prepared. The obtained cement composition (B3) contained 1% water and 0.48% dry weight as a high performance water reducer based on the early strength Portland cement used. Regarding this cement/composition (B3), after 5 minutes have passed immediately after the preparation, the aggregate and the mixing water are supplied into a mixing mixer so that they come into contact with the mixing water, and mixing is performed.
manufactured concrete.

Example 1 Early-strength Portland cement was supplied into a mixer together with aggregate and stock mixing water without undergoing the above-mentioned special treatment, and mixed to produce concrete.

Lateral tag - Early strength Boltland cement without the above special treatment is fed into a stock mixer with mixing water to which aggregate and high-performance water reducer (BNS) have been added, and mixed. , produced concrete.

2) Fresh concrete test Regarding the fresh concrete obtained in 1) above,
A concrete test was conducted for each cement composition (Bl) (B2) * or (B3). The test results are shown in Table-2.

The fluidity of concrete produced according to the method of the present invention is
This is a significant improvement over those produced by conventional methods. That is, as shown in 5-1 of Examples 1 to 3, the mortar flow value is 190 to 202 mm.
This can be seen from the fact that the fluidity has been significantly improved. Furthermore, as is clear from Table 2, the fluidity is naturally improved, and the unit water amount for the same slump is slightly reduced. In addition, the improved water-reducing property reduces the amount of breathing, which reduces the settling of mortar or concrete after pouring, suppressing the occurrence of settlement cracks, and improving strength development. A highly durable mortar or concrete is obtained.

An example of producing fresh concrete using an uninvented method is shown in a flow sheet (FIG. 1).

In 1E1, the powdered cement composition is supplied from the cement storage bin 1 (E in the figure) to a continuous mixer for special treatment (F in the figure) and subjected to special treatment. The cement composition discharged from the continuous mixer described in 1 is stored in the cement storage bin 2.
(G in the figure), cement hopper (H in the figure) or cement scale (■ in the figure). Alternatively, the cement may be temporarily stored from the cement storage bin 2 (G in the figure) in a cement hopper (in the figure) bin, and then supplied to a cement measuring device (D in the figure). Next, use the cement measuring device (■ in the diagram), Myokei f
The measured and purified materials are supplied to the concrete mixing mixer (J in the diagram) from the f-meter (K in the diagram), the gravel meter (L in the diagram), and the mixing water meter (M in the diagram). Ru. Each material is thoroughly mixed in a mixing mixer and discharged as fresh concrete.

[Effects of the invention] The method for producing mortar or concrete according to the present invention can greatly improve the performance of mortar or concrete, and the properties of the mortar or concrete are significantly improved, compared to the method of producing mortar or concrete according to the present invention. be done.

l) In the case of the method of the present invention, if the amount of mixing water used in preparing a cement mixture such as cement mortar, cement grout, or concrete 1 is the same as that used for the above-mentioned cement mixture manufactured by a conventional method, Their liquidity becomes significantly greater.

Therefore, workability, filling properties of the cement mixture, self-leveling properties, etc. are improved, and furthermore, the quality of the obtained cement mixture is excellent, and the above-mentioned cement mixture can be transported for a long time.

2) In the case of the method of the present invention, when the consistency of the cement mixture such as cement mortar, cement grout, or concrete is the same as that of a cement mixture produced by a conventional method, the amount of water required for mixing is:
Noticeably small.

Therefore, the fresh mortar or fresh concrete produced by the method of the present invention has the following excellent properties in mortar or concrete after hardening.

■ Since the unit amount of water used is significantly smaller, strength and durability are significantly greater.

(Because drying shrinkage is reduced, drying shrinkage cracks are less likely to occur.)

■ Since the amount of breathing is reduced, there is less settling of mortar or concrete 1 note during pouring, and there are fewer settlement cracks.

■ Since the unit amount of water used is significantly smaller, mortar Maroku has greater concrete density and excellent durability.

■ When pouring mortar or concrete of the same strength, it is possible to reduce the amount of cement per unit, which reduces the initial hydration calorific value and reduces the occurrence of cracks due to thermal stress. I can do it.

BRIEF DESCRIPTION OF THE DRAWINGS The attached drawing is a flow sheet showing an example of the production of fresh concrete by the method of the present invention.

Claims (1)

[Scope of Claims] 1) A method for producing fresh mortar or fresh concrete, comprising: continuously supplying a powdered cement composition; Under conditions of distributed scattering,
The composition is allowed to fall, and during the fall, water containing a cement additive or water not containing it is used in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the cement composition, homogeneously spraying onto the cement composition;
During this time, the cement particle surface is subjected to a modification treatment by being subjected to a shearing action, and the time until the obtained powdered cement composition comes into contact with mixing water is set at 3 minutes or more. A method for producing mortar or concrete, characterized in that it is mixed with aggregate and mixing water in a mixing mixer. 2) The method for producing mortar or concrete according to claim 1, wherein the powdered cement composition is a hydraulic cement or a composition obtained by mixing this with an inorganic fine powder. 3) The method for producing mortar or concrete according to claim 2, wherein the inorganic fine powder is one or more powder materials selected from the group consisting of blast furnace slag powder, fly ash, or fine silica powder.